: The script captures keystrokes, including usernames, passwords, and private messages, as they are typed. Exfiltration : The recorded data is sent to a Command-and-Control (C&C) server
Regularly check your chrome://extensions page and remove any that you no longer use.
document.addEventListener('keydown', function(event) let key = event.key; // Logic to send this key to a server or store it locally );
The malicious code is often hidden (obfuscated) so that reviewers cannot easily see what it does, as discussed on Reddit .
Modern extensions often go beyond simple keystrokes, acting as "form grabbers" to capture more data at once. They inject JavaScript to add event listeners for forms, automatically saving the data of username , email , and password fields upon submission, often capturing complete login contexts even over encrypted HTTPS connections. keylogger chrome extension work
Here is a comprehensive look into how these extensions operate, the permissions they exploit, and how users can protect themselves. The Core Architecture of Chrome Extensions
to the browser window. Every time you press a key, the extension captures the specific character. Stealthy Logging
Scripts that run persistently or on-demand in the background, independent of the active tab. They handle data storage, network communications, and cross-tab management. Step-by-Step: How a Keylogger Chrome Extension Works
Many users assume that password fields are safe because characters turn into dots ( ••••• ). However, input elements with type="password" only mask the visual display for human onlookers. To the JavaScript DOM running inside the tab, the plain-text value of the input field is completely visible and readable. The keylogger grabs the exact string value as it is being entered. 5. Passing Data to the Background Script Modern extensions often go beyond simple keystrokes, acting
Once captured, keystrokes must be stored. Extensions often use chrome.storage.local to save keylogs directly on your machine, along with metadata like the URL and timestamps. The "Chrome Event Logger" extension, for example, records keystrokes, clipboard activity, and even periodic screenshots, storing them locally in categorized logs.
Used to temporarily cache logged keystrokes locally on the user's machine if the system goes offline, ensuring no data is lost before exfiltration.
If you suspect an extension is behaving maliciously, you can turn on "Developer mode" in chrome://extensions/ . Click on the "service worker" or "background page" link next to the suspicious extension to open the DevTools window. Monitor the to see if the extension is silently sending data to an unfamiliar, external IP address or domain. 4. Utilize Security Features
The blueprint of the extension. It defines the name, version, required permissions, and scripts that Chrome must execute. The Core Architecture of Chrome Extensions to the
: "Stealthy" extensions may be marketed as productivity tools (like PDF converters) but secretly log passwords, credit card numbers, and messages.
: Some extensions like Onscreen key logger are legitimate tools used for presentations or demos to show viewers which keys are being pressed.
Logged data is sent to an attacker-controlled server or saved locally using:
The primary function of any keylogger—to record keystrokes—is made possible through the extension's ability to inject its own code into web pages. This is achieved using a piece of code, often a , which runs within the context of the pages you visit.